Principal source:
Compiler: Dr. Justin Gerlach, The Nature Protection Trust of Seychelles, Cambridge, UK & IUCN/SSC Invasive Species Specialist Group (ISSG)
Review: Dr. Justin Gerlach, The Nature Protection Trust of Seychelles, Cambridge, UK.
Publication date: 2006-07-24
Recommended citation: Global Invasive Species Database (2024) Species profile: Clidemia hirta. Downloaded from http://www.iucngisd.org/gisd/species.php?sc=53 on 08-12-2024.
\r\nPhysical: Manual weeding may be effective for small populations. In healthy ecosystems Clidemia hirta's dominance is a temporary phenomenon with forest trees overshading it within 7 years.\r\n
\r\nGround disturbance created by feral pigs (Sus scrofa) plays a major role in the establishment of C. hirta and other populations of alien species in Hawaii (Smith 1993, Stone et al. 1993, in Peters 2001). These pigs are native to North Africa and Eurasia, including Malaysia, but are currently found on many oceanic islands and all continents except Antarctica (Lever 1985, in Peters 2001). They are omnivorous and obtain a substantial portion of their food by grubbing for roots, bulbs, fungi, invertebrates, and other belowground material (Aplet et al. 1991, Fensham 1993, Kotanen 1995, in Peters 2001). Severely grubbed areas may extend for more than a hectare, but are typically composed of many small (ca 1 m2) patches of ground disturbance. Through trampling, rooting, and preferential feeding, feral pigs in Hawaii have disturbed natural plant communities dramatically (Aplet et al. 1991, Stone 1993, in Peters 2001). Wild pigs may also act as agents of dispersal for introduced species including C. hirta(Stone and Loope 1987, in Peters 2001). Because of this link the possibility exists of controlling C. hirta by managing pig populations, especially at places where the link between soil disturbance and invasive plant spread has been established, such as at the Pasoh Forest Reserve (Malaysian peninsula).\r\n
\r\nDisturbance is a key element in the establishment and invasion of C. hirta. Wildfires, landslides, windstorms and other forms of soil disturbance (such as pig rooting) accelerate the dominance of this weed (Smith Undated; Peters 2001). In its native environment plants are confined to open areas and only become dominant about twelve months after disturbance, such as in slash-and-burn agricultural areas (Burkhart Pers. Comm, in Smith Undated). All new range extensions in Hawaii begin along the open edges of trails or other disturbed areas. In order to keep the weed out of an area the primary management objective should be to minimise and prevent disturbance (Smith Undated). \r\n
\r\nAll efforts to eradicate newly established populations of C. hirta in Hawaii failed when they were not initiated before first fruit set (Smith Undated). There have been many well-meaning attempts by volunteer groups to control the spread of C. hirta through pulling it by hand, unfortunately the effort is likely to fail. The seed bank produced by these plants is colossal over a very short period of time (Smith Undated). In order to effectively control an infested area by mechanical means eradication efforts must be conducted at least once a year for up to 10 years. Only two instances of successful control, Kamakou (Moloka'i) and Pu'u Kukui trail (Maui) are known (Smith Undated). Clidemia is susceptible to a number of herbicides but will regenerate unless further applications are made. Chemical control does not appear to be practical in Hawaii's native ecosystems, particularly those difficult to access (Smith Undated).\r\n
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